Chronic kidney disease (CKD) biomarkers

Chronic kidney disease (CKD) is characterised by a gradual loss of kidney function over time. This affects the kidney's ability to filter blood and leads to a build-up of waste and fluid inside the body. CKD can result in other problems such as high blood pressure, heart disease and anaemia (KHA 2023, 2024).

The biomarkers related to impairment of kidney function that were measured were:

• urinary albumin
• urinary creatinine
• serum creatinine.

From these results, the albumin/creatinine ratio (ACR) and the estimated glomerular filtration rate (eGFR) were calculated. Self-reported data on kidney disease was also collected in other survey components of the IHMHS.

It is important to note that while abnormal ACR or eGFR test results may indicate impaired kidney function, they cannot provide a diagnosis for CKD based on a single test alone. CKD can only be confirmed if abnormal results are detected for at least three months (KHA 2024).

Laboratory test information, including analysis methods and machines used to measure CKD biomarkers, is available from the Downloads page.

This is the second time the ABS has collected information on urinary albumin, urinary creatinine, ACR ratio, serum creatinine and eGFR. Information on these biomedical indicators was previously collected in the NHMS 2011–12 and the NATSIHMS 2012–13. For information on time series comparability, see Comparing biomedical collections over time.

Urinary albumin, urinary creatine, the ACR ratio, serum creatinine and eGFR data has been reported in other non-ABS surveys. However, caution must be taken when interpreting results due to the differences in scope, assay and the instrument used, and any thresholds applied in the final analysis.

Creatinine is a by-product of muscle metabolism, which circulates around the body in the blood (KHA 2025a). Serum creatinine results were used to calculate eGFR.

Serum creatinine results were obtained for all persons aged 12 years and over who provided a blood sample. Fasting was not required for this test.

Serum creatinine levels were measured at the Douglass Hanly Moir Pathology (DHM) laboratory, by the Enzymatic method traceable to isotope-dilution mass spectrometry. The serum creatinine test measures the amount of creatinine circulating in the blood at the time of the test.

There is no consensus on the epidemiological cut-off reference values for measuring creatinine in serum. As such, no cut-off points have been defined.

Albumin is a protein that is produced by the liver and is found in the bloodstream where it is important for maintaining fluid balance and carrying hormones, vitamins and enzymes throughout the body. As kidney function declines, albumin leaks into a person’s urine. Albuminuria is the term used when a person has abnormal levels of albumin in their urine (KHA 2025b). A urine albumin result is used with a urine creatinine result to calculate ACR.

Urinary albumin results were obtained for persons aged 5 years and over who provided a urine sample. Fasting was not required for this test.

Urinary albumin levels were measured at the DHM laboratory by the Turbidimetric/Immunoturbidimetric method. The albumin test measures the amount of albumin in the urine at the time of the test (spot test).

There is no consensus on the epidemiological cut-off reference values for measuring albumin, independently in urine. As such no cut-off points have been defined.

Points to be considered when interpreting data for this topic include the following:

• Albumin test results do not confirm a specific diagnosis without consultation with a health professional.
• There are several different test methods to measure albumin levels and each test method may produce different results. The data from this topic should therefore be used with caution when comparing albumin results from other studies using a different test method.

Creatinine is a by-product of muscle metabolism, which circulates around the body in the blood. Healthy kidneys filter creatinine out of the blood and it exits the body as a waste product in urine (KHA 2025a). A urinary creatinine result is used with a urinary albumin result to calculate ACR.

Urinary creatinine results were obtained for persons aged 5 years and over who provided a urine sample. Fasting was not required for this test.

Urinary creatinine levels were measured at the DHM laboratory by the Kinetic alkaline picrate method. The creatinine test measures the amount of creatine in the urine at the time of the test (spot test).

There is no consensus on the epidemiological cut-off reference values for measuring urinary creatinine. As such, no cut-off points have been defined.

Points to be considered when interpreting data for this topic include the following:

• Urinary creatinine test results do not confirm a specific diagnosis without consultation with a health professional.
• There are several different test methods to measure creatinine levels, and each test method may produce different results. The data from this topic should therefore be used with caution when comparing creatinine results from other studies using a different test method.
• There are issues with the validity of using urinary creatinine excretion as an index of muscle mass.

eGFR measures how well the kidneys filter waste from the blood and is considered the best overall measure of kidney function (KHA 2025a). eGFR helps determine if a person has kidney damage. A low filtration rate means that the kidneys are not working properly (KHA 2025a).

The eGFR was calculated using a person’s serum creatinine (SCr) result, age, and sex. The DHM laboratory used the 2009 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations (Levey et al. 2009; Johnson et al. 2012b; Levey and Eckfeldt 2017). These equations were also used in the NHMS 2011–12 and the NATSIHMS 2012–13. eGFR results were published only for people aged 18 years and over, as the CKD-EPI equations cannot be used for children without adjustments (Björk et al. 2021).

Cut-off reference values for normal and abnormal results were sourced from the CKD management guidelines by Kidney Health Australia (KHA 2024, 2025a). These guidelines are based on epidemiological data and publications of major clinical trials. The following cut-offs were used, where the result is expressed relative to a 'standard' body surface area of 1.73m²:

• normal eGFR levels ≥60 mL/min/1.73m²
• abnormal eGFR levels <60 mL/min/1.73m².
   

Points to be considered when interpreting data for this topic include the following:

• eGFR test results do not confirm a specific diagnosis without consultation with a health professional.
• There are several different test methods and equations to measure eGFR levels and they may produce different results. The data from this topic should therefore be used with caution when comparing eGFR results from other studies using a different test method or equation.
• The CKD-EPI equations are only validated for use with isotope dilution mass spectrometry. Traceable creatinine assays and coefficients for race are not included, therefore results should be interpreted with care when comparing this data with other sources (Delgado et al. 2021; Bailey and Farnsworth 2022; Fu et al. 2023).

ACR is measured by dividing the amount of albumin (a protein) in the urine by the amount of creatinine (a metabolism byproduct) in the urine. It is used to determine albuminuria, the presence of excessive amounts of the protein albumin in the urine (KHA 2023).

The degree of albuminuria relates to the severity of CKD and greater likelihood of progression to end stage CKD. Reduction in the amount of albuminuria is associated with improved outcomes (KHA 2025b, 2024; Johnson et al. 2012a).

Sex dependent cut-off reference values for albuminuria were sourced from the Royal College of Pathologists of Australasia manual (RCPA 2024). Cut-offs are based on epidemiological data and publications of major clinical trials (KHA 2024). The table below shows cut-offs used for albuminuria (ACR levels):

ACR was calculated for persons aged 5 years and over, who provided a urine sample. Results were only published for persons aged 18 years and over as there is no validated ACR level for determining impaired kidney function for children for spot urine samples.

Points to be considered when interpreting data for this topic include the following:

• ACR was calculated using urinary albumin and creatinine levels taken from a spot test only.
• ACR test results do not confirm a specific diagnosis without consultation with a health professional.
• Other factors such as urinary tract infections, high protein diets or heavy exercise within 24 hours of the test are known to affect ACR results (KHA 2024; Johnson et al. 2012a). As a result, the data should be interpreted with care.
• There are several different test methods for measuring urinary albumin and creatinine, which may produce different results. The data from this topic should be used with caution when comparing ACR results from other studies using different test methods or equation.

Impaired kidney function prevalence rates were derived using a combination of respondents’ eGFR and ACR. There are five stages of CKD, ranging in severity from Stage 1 to Stage 5. During stages 1 and 2, a person might not notice any symptoms, however at stage 5, they are generally reliant on dialysis or a kidney transplant to stay alive (KHA 2023).

Early stages of CKD are defined by abnormal ACR and normal eGFR test results. Later stages of CKD are defined by abnormal eGFR test results only. The following cut-offs were used for CKD stages:

Points to be considered in interpreting data for this topic include the following:

• While abnormal eGFR or ACR test results may indicate impaired kidney function, they cannot provide a diagnosis for CKD based on a single test alone. CKD can only be confirmed if albuminuria or eGFR of less than 60 mL/min/1.73m² is persistent for at least three months. For more information about these tests, see the relevant eGFR and ACR topic pages.
• Self-reported information about kidney disease was collected in other IHMHS components. Respondents were asked whether they had ever been told by a doctor or a nurse that they had kidney disease and whether they currently had the condition. Respondents with kidney disease were assumed to have the condition long-term.

Treatment for individuals with CKD by health professionals is determined by combining information on the CKD stages of disease based on eGFR results with ACR results and information on other conditions, noting these should be results over a 3-month period. Different stages of kidney function will require different management strategies (KHA 2024).

In general, those with an eGFR of ≥60 mL/min/1.73m² require monitoring unless haematuria (blood in the urine), structural or pathological abnormalities are present (Australian Urology Associates 2024). Progressive treatment is required for individuals as kidney function stage increases (KHA 2024).

Other factors considered by health professionals in managing CKD are:

• age
• blood pressure
• weight
• smoking
• fasting lipid levels
• cardiovascular risk
• oedema
• calcium and phosphate levels
• parathyroid hormone (if eGFR <45 mL/min/1.73 m²)
• diabetic status.

Management of early CKD includes steps to reduce cardiovascular disease risk (KHA 2024). For more information, refer to Australian CVD risk calculator.

Australian Urology Associates (AUA) (2024), Haematuria, AUA website, accessed 20/02/2025.

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Kidney Health Australia (KHA) (2023), What is Chronic Kidney Disease?, KHA, accessed 20/02/2025.

Kidney Health Australia (KHA) (2024), Chronic Kidney Disease (CKD) Management in Primary Care (5th edition), KHA, accessed 20/02/2025.

Kidney Health Australia (KHA) (2025a), Estimated glomerular filtration rate (eGFR): Factsheet, KHA, accessed 20/02/2025.

Kidney Health Australia (KHA) (2025b), Albuminuria, KHA, accessed 20/02/2025.

Levey AS, Stevens LA, Schmid CH, Zhang Y, Castro III AF, Feldman HI, Kusek JW, Eggers P, Van Lente F, Greene T, Coresh J; CKD Epidemiology Collaboration (2009), A New Equation to Estimate Glomerular Filtration Rate, Annals of Internal Medicine, 150(9):604-612, accessed 20/02/2025.

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Royal College of Pathologists of Australasia (RCPA) (2024), ’Albumin urine‘, RCPA Manual, RCPA website, accessed 20/02/2025.